84.42 Chapter 31. Solutions of linear systems with constant coefficients. Supplementary problems

84.42.1 problem 31.8
84.42.2 problem 31.9
84.42.3 problem 31.10
84.42.4 problem 31.11
84.42.5 problem 31.12
84.42.6 problem 31.15
84.42.7 problem 31.16